This invention relates to an electrical connector In which crosstalk between two or more pairs of signal carrying contacts is reduced.
There is a problem in connectors with multiple pairs of conductors, where each pair is required to carry individual signals, as there is the risk of cross coupling of signals due to electrostatic (capacitive) and magnetic (induction) coupling. Such cross coupling is called crosstalk and becomes worse as frequencies of signals are increased. The crosstalk results from the capacitive and inductive coupling between nearest lines of two pairs, which dominates the opposite phase and canceling effect from the furthest lines of the pair, of a balanced two wire system. This results in effectively a differential coupling of each line of each pair and the lines of the other pair. The problem is sometimes worsened by wiring conventions for example in the EIA/TIA 568B wiring practice for an eight contact in line connector, contacts 1 and 2 form the orange pair, contacts 3 and 6 form the green pair, contacts 4 and 5 form the blue pair and contacts 7 and 8 form the brown pair. It will be appreciated that in such a configuration crosstalk is a major problem between blue and green pairs as each line of each pair lies adjacent a line of the other pair and there is electrostatic and electromagnetic coupling between them. To a lesser extent there is coupling between green and both orange and brown because one line of each pair lies adjacent a line of the other pair.
Attempts have been made to reduce the effect of crosstalk in adjacent lines of electrical connectors. For example in U.S. Pat. No. 5,547,405 by Pinney (present inventor), et al., owned by the present assignee, there is disclosed an electrical connector which has four contacts extending between input terminals and output terminals. In order to reduce crosstalk between pairs of contacts a lateral extension from one contact overlies a second contact. The lateral extension does not carry current but provides capacitive coupling between the contacts to produce crosstalk in opposition to crosstalk induced between the mutually closest terminals. Whilst the construction described in that patent specification provides some cross talk compensation and is relatively simple to manufacture it has been discovered that improvements in cross talk cancellation are possible. The present invention seeks to provide a connector having improved crosstalk cancellation.
According to the invention there is provided an electrical connector comprising at least four contacts extending between input and output terminals, in which the mutually most distant contacts of different particular assigned signal carrying pairs of said contacts is arranged to provide coupling therebetween to induce compensating crosstalk. The compensating crosstalk is in opposition to crosstalk induced between the mutually closest contacts of the different assigned signal carrying pairs, wherein the path lengths of the mutually most distant contacts are extended to enhance a phase opposition relationship between the mutually opposed cross talks, thereby to reduce overall crosstalk.
A third contact of a group of four primarily longitudinally extending contacts has a lateral extension. The extension includes a suppressing section that extends parallel and adjacent to a first contact of the group. A pair of connecting sections each connects an end of the suppressing section to the third contact, and has a part that extends across a second contact that lies between the first and third contacts. One of the connecting sections can have a lengthening portion to cause a phase shift. The width of the suppressing section is less than twice its height, to minimize capacitive coupling.
In order that the invention and its various other preferred features may be understood more easily, embodiments thereof will now be described, by way of example only, with reference to the drawings.